The long term objective of this investigation is directed towards understanding more fully the biochemical and physiological importance and function of two cell surface components, the poly (gamma-D-glutamyl) capsule of Bacillus licheniformis and polymers containing polysialic acid residues in Escherichia coli. Effort during the past few years has been concerned with the structure and biosynthesis of these cell envelope polymers. On the basis of work already accomplished (determination of the structure of the poly (gamma-D-glutamyl) capsule; biosynthetic studies on the membranous polyglutamyl synthetase and sialyltransferase complex; isolation, characterization and role of undecaprenyl phosphate in sialyl polymer synthesis), these objectives are a logical continuation of studies currently in progress which include elucidation of the precise molecular events whereby membranous enzyme interactions participate in the synthesis and assembly of these surface components. In sialyl polymer synthesis, major emphasis will focus upon: 1) the mechanism of assembly of the sialyltransferase complex; 2) a detailed study of the mechanism of polymerization; and 3) further structural studies on the nature of the biosynthetic and in vivo polymers. In addition, studies recently initiated to study the interaction of spin-labeled polyisoprenyl phosphate derivatives (e.g. undecaprenyl phosphate) with model phospholipid membranes and reconstituted membrane vesicles possessing sialyl-transferase activity will be continued. Future studies on the biosynthesis of the poly (gamma-D-glutamyl) polymers will be directed at understanding the mechanism of activation, racemization and polymerization of this unique capsular polymer.